20A ACS712 Current Sensor

20A ACS712 Current Sensor Module Detailed Explanation

What is it?

The ACS712 20A Current Sensor Module is a Hall-effect'based sensor used to measure AC or DC current in a circuit.

It converts current flowing through a wire into a proportional analog voltage that a microcontroller (Arduino, ESP32, etc.) can read.

How It Works

The module is based on the Hall Effect:

• Current flows through a copper conductor inside the sensor

• This creates a magnetic field

• The Hall sensor detects this field

• Converts it into a voltage output

The output voltage is linearly proportional to the current

Pin Configuration

Module Pins:

Current Terminals:

The current-carrying wire must pass through the sensor terminals

Key Specifications

• Current range: 20A to +20A

• Operating voltage: 5V

• Output: Analog (05V)

• Sensitivity: 100 mV per Ampere

• Zero current output: ~2.5V (midpoint)

• Measures: AC + DC current

Important Concept (Very Important)

Center Voltage (Offset)

• When current = 0A rent voltage increases

• Negative current voltage decreases

This allows measurement of bidirectional current (AC/DC)

Working Formula

To calculate current:

I=Vout2.50.1I = \frac{V_{out} - 2.5}{0.1}I=0.1Vout2.5

Where:

• VoutV_{out}Vout = sensor output voltage

• 0.1 = 100 mV/A sensitivity

Working Flow

Current Flow Magnetic FieldHall Sensor Detects FieldVoltage Output (Analog)Microcontroller Reads ValueConvert to Current (Amps)

Applications

• Battery monitoring

• Power consumption measurement

• Smart energy meters

• Motor current sensing

• Electrical isolation (safe measurement)

• Easy interface with Arduino

• Good accuracy for mid/high currents

Limitations (Important)

• Not suitable for very small currents (<100mA)

• Output is noisy needs filtering

• Accuracy depends on calibration

Community experience confirms it struggles with very low current measurement due to low sensitivity

Arduino Connection

• VCC 5V

• GND GND

• OUT A0

Example Use

Measure appliance current:

• Connect load through sensor

• Read analog voltage

• Convert to current

• Display on serial monitor

Practical Tips

• Always for stable readings

• Avoid external magnetic interference

• Choose correct version:

  • 5A high precision

  • 20A general use

  • 30A high current

ACS712 Variants Comparison

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